Mixer



' K. E. MCCONNAUGHAY MIXER May 2,7, 1947.

Filed Nov. 4, 1944v i! 29 2f /la 2 2 IN V EN TOR. KENNETHE-l`7"(0NNm/c//;

Patented May 27, 1947 UNITED STATES PATENT OFFICE MIXER Kenneth E.McConnaughay, West Lafayette, Ind.

Application November 4, 1944, Serial No. 561,849

6 Claims. 1

My invention relates to a machine for producing a bituminous pavingcomposition and more particularly to a machine suitable for use inperforming the steps of drying aggregate, mixing the dried aggregatewith a bituminous binder, and supplying heat to the binder and aggregateas they are being mixed together. l

It is the object of my invention to produce a machine which will dryaggregate, mix it with a bituminous binder, and supply heat to theaggregate and a binder as they are being mixed. A further object of myinvention is to produce such a machine in which a single source ofheated air or gases supplies heat Iboth to the mixture of aggregate andbinder and to the aggregate alone before it comes into contact with thebinder. yAnother object of my invention is to produce a maehine of thetype just described which can be simply constructed and economicallyoperated.

In carrying out my invention, I employ a rotatable drum adapted toreceive aggregate at one end. Near the opposite end of the drum Iprovide binder-supplying means and means, operative by virtue ofdrum-rotation, to mix the aggregate and binder. A burner or othersuitable source of hot air or hot gases is located at the discharge endof the mixing means in the position to discharge its heated air orheated gases into the drum and above the material being mixed by themixing means.

The accompanying drawing illustrates my invention: Fig. 1 is a verticalaxial section through 011e Oim f mXeI; Fig. 2 is a transverse verticalsection on the line 2-2 of Fig. 1; Fig. 3 is a fragmental vertical axialsection showing a modification of the mixer of Figs. 1 and 2; Fig. 4 isa side elevation, in partial section, illustrating a modied form ofmixer; and Fig. 5 is a fragmental vertical section illustrating amodification of the mixer shown in Fig. 4.

The mixer illustrated in Figs. 1 and 2 comprises a drum I8 supported:for rotation about a hori- Zontal axis by rollers I I on a frame I2.The drum is adapted to be rotated by any convenient means, the meansillustrated comprising an electric motor I5 operatively connected to thedrum by a chain -drive I6.

A vertical plate I8 supported from the frame I2 covers the inlet end ofthe drumvand is provided opposite the lower portion of the drum with anopening I9 through which aggregate may be admitted to the drum from ahopper or chute 20. Opposite the upper portion of the drum Ill, theplate I8 is provided with an exhaust opening 2l communicating with anexhaust stack 2,2.

The drum I Il is provided interiorly with flights which are adapted bothto lift and dump aggregate so that it will drop across the interior ofthe drum and to cause the aggregate to be fed through the drum to thedischarge end thereof.

, 2 As shown, the flights include relatively short nights 25 set at aslight helical angle and two elongated flights 25 parallel to thedrum-axis.

At the discharge end of the drum I mount on the frame I2 a cylindricalcasing '28. ISuch casing is generally co-axial with the drum I0, but isof larger diameter than the drum. The drum desirably extends into thecasing 28 for a short distance, and the annular space between the casingand drum is substantially closed by an annular wall 29.

Carried by the drum are a plurality of bladesupporting members 30 whichmay be continuations of the flights 26 and which extend axially from thedischarge end of the drum into the casing 28. Each of the members 30carries a series of helically disposed mixing blades 3| adapted to mixmaterial in the lower portion of the housing 28 and to cause-it to befed axially of the housing toward the discharge end thereof. Binder formixing with the aggregate may be supplied thereto by a spray bar 33extending into the housing v28 from the discharge end thereof.

At the discharge end of the housing 28 I mount on the frame I2 a burner35 or other means for supplying heated air to the housing 28 and drumI0. Desirably, this burner ismounted `in an axial position to dischargea stream of air through the housing and drum toward the exhaust opening2 I.

In the operation'of the device illustrated in Figs. 1 and 2, aggregateis supplied to the drum I8- through the opening I9. As the drum rotates,such aggregate is repeatedly elevated by the flights 25 and droppedthrough Vthe stream of heated air emanating from the burner 35. At thesame time, because of the helical inclination of the flights 25, theaggregate is caused to progress axially through the drum. When theaggregate is discharged from the end of the drum into the housing 28, itcomes into association with a bituminous binder vsupplied through thepipe 33. The blades 3l, which rotate with the drum I0, serve to mix theaggregate` and binder together and to feed the mixture toward and out ofthe discharge end of the housing. It will be obvious that during themixing operation the mixture will receive considerable heat from thestream of hot gases and air discharged by the burner 35.

If it is considered desirable to prevent any possibility of directcontact between the bituminous mixture and the products of combustionfrom the burner 35, as might be the case Where the binder contains avolatile solvent, I may mount within the housing 28 an annular shieldserving as a conduit for the gases discharged by the kburner 35. Asshown in Figs, 1 and 2, this shield may take the form of a sheet-metalcylinder' `supported from the frame I2 and extending suiciently far intothe housing 28 to confine the hot gases during their passage throughthat part of the housing in which the mixing operation is performed.

The modification of the invention illustrated in Fig. 3 is substantiallythe same as shown in Figs. 1 and 2 except that the cylindrical housing28 is replaced by a conical housing 28' disposed with its larger endtoward the drum l0. With this arrangement, the bottom wall of thehousing 28' slopes upwardly toward the discharge end of the housing,thereby preventing unmixed binder from running out of the housing underthe influence of gravity and making it possible to maintain adjacent theinlet end of the housing a pool of excess binder. In this construction,the mixing blades 3l' carried by the members 3D are similar tothe bladesD3| but are made of gradually decreasing length toward the discharge endof the housing.

In the modification illustrated in Fig. 4, a drum 40 is supported forrotation about an inclined axis by rollers 4l mounted on a frame 42. Theupper end of the drum, which is the inlet end, has associated with it aplate 43 similar in purpose and vconstruction to the plate I8 of Fig. land provided with an aggregate-receiving opening 44 and an exhaustopening 45,V the latter communicating with `a stack 46.

Becauseof the inclined position of the drum 4U, it is unnecessary toprovide therein any means for feeding aggregate therethrough. It isstill desired, however, that the aggregate be repeatedlyelevated anddropped through the stream of heated air and gases within the drum; andfor this purpose'I provide the drum interiorly with'longitudinallyextending ights 48. These flights extend from the inlet end of the drumto the point at which the aggregate-drying operationis to terminate andthe mixing operation is to begin. The drum, however, extends for aconsiderable distance beyondthis point,

Supported from the frame 42 at the discharge end of the drum 40, andextending axially inwardly of the drum. is a blade-supporting membei-'5Uwhich, within the drum, carries a series of downwardly extending mixingblades l adapted'to mix and stir aggregate in the lower portion of thedrum. Binder for mixing with the aggregate is supplied byV a spray-bar52 extending axially into the drum from the discharge end thereof. Aburner 53 or other source of heated air is disposed similarly to theburner 35 of Fig. 1 to discharge axially into the drum toward theexhaust opening 45.

The operation of the machine shown in Fig. 4 is substantially the sameas that of the machine shown in Figs. 1 and 2. The mixing operation,however, instead of being performed by rotating blades in a stationarydrum, is performed by stationary Iblades located within the rotatingdrum 4'0.

Because of the inclined position of the cylindrical drum 4D, any excessbinder supplied from the spray bar 52 would run out of the drum underthe inuence of gravity. To prevent this, I may use the constructionshown in Fig, 5. In such construction, the 'drum 4D is cylindrical fromits inlet end to the point at which the flights 48 terminate. Theremainder of the drum, between such point and the discharge end, is ofconical form, as indicated at 40'. The taper of the conical portion 49is such that at its bottom it slopes upwardly toward the dischargeopening, thus preventing the escape of any excess binder.

I claim as my invention:

1. In a mixer for preparing a bituminous paving composition, a rotatabledrum having an inlet end for the reception of aggregate and a dischargeend, said drum being provided near its inlet end with internal flightswhich lift aggregate and permit it to drop across the interior of thedrum as the drum rotates, means for supplying a bituminous binder toaggregate passing through the drum, said binder-supply means discharginginto said drum at points located wholly beyond said flights in thedirection of aggregate-movement through the drum whereby none of thematerial lifted by said ilights will contain binder, means operative inthe rotation of the drum for mixing the aggregate and binder togetherbelow the drum-axis, and means for forming and directing a stream ofheated gases above the mixing aggregate and binder and axially throughthe drum toward the inlet end thereof.

2. The invention set forth in claim l with the addition of a stationaryhousing into which the discharge end of said drum extends, said housinghaving an arcuate bottom substantially con centric with the drum, saidmixing means comprising a series of mixing blades carried by said drumand extending into said housing.

3. The invention set forth in claim 1 with the addition that said mixingmeans comprises a stationary blade-support extending axially into saiddrum from the discharge end thereof and a series of stationary mixingblades carried by said blade-support and projecting downwardly therefrominto proximity to the inner surface of the drum.

4. In a mixer for preparing a bituminous paving composition, a rotatabledrum having an inlet end for the reception of aggregate and a dischargeend, said drum being provided near its inlet end with internal flightswhich lift aggregate and permit it to drop across the interior of thedrum as the drum rotates, means for supply ing a bituminous binder toaggregate passing through the drum, said binder-supply means discharginginto said drum at points located wholly beyond said flights in thedirection of aggregate-movement through the drum whereby none of thematerial lifted by said flights will contain binder, means for mixingthe aggregate and binder together below the drum-axis, and means for.forming and directing a stream oi heated gases above the mixingaggregate and binder and axially through the drum toward the inlet 'endthereof.

5. The invention set forth in claim 1 with the addition of a stationaryhousing into which the discharge end of said drum extends, said housinghaving an arcuate bottom substantially concentric with the drum andsloping upwardly away from the drum, said mixing means comprising aseries of mixing blades carried by said drum and extending into saidhousing.

6. In a mixer for preparing a bituminous paving composition, a rotatabledrum having an inlet end for the reception of aggregate and a dischargeend, said drum being provided near its inlet end with internal flightswhich lift aggregate and permit it to drop across the interior of thedrum as the drum rotates, means located axially beyond said flights forsupplying a bituminous .binder to aggregate passing through the drum,means operative in the rotation of the drum for mixing the aggregate andbinder together below the drum-axis, and means for forming and directinga stream of heated gases above the mixing aggregate and binder andaxially through the drum toward the inlet end thereof, said mixing meansincluding a blade-support,

The following references are of record in the file of this patent:

UNITED STATES PATENTS an aggregate-support, and mixing blades on theNumber Name Date blade-support in position to engage aggregate on2,298,016 Lincoln Oct. 6, 1942 the aggregate-support, one of saidsupports be- 5 2,305.938 Turnbull Dec. 22, 1942 ing rotatable with thedrum and the other being 1,836,754 Hepburn Dec. 15, 1931 stationary. TEN

KENNETH E. MCCONNAUGHAY. FOREIGN PA Ts Number Country Date REFERENCESCITED 10 35,737 Denmark Feb. 27, 1926

